Recent years have seen more vehicles in which a camera is mounted so that the driver of the vehicle can observe the side, rear, and other peripheral regions of the vehicle via an in-vehicle monitor. There are also apparatuses under development that carry out image processing or the like using a captured image acquired by the camera, and support parking and other driving operations. In such an apparatus, the camera for acquiring the captured image, which is the base for computing information used for positioning the vehicle and for other purposes, requires particularly high optical axis precision. Such a high optical axis precision is not easily obtained during mounting, and after the camera has been mounted, high precision can be achieved by calibrating the optical axis. In order to carry out such calibration, the calibration target used for calibration must be adequately detected. Art for detecting such a calibration target is disclosed in, e.g., Patent Document 1 cited below.
Patent Document 1 discloses an optical axis displacement detection apparatus for detecting displacement of the optical axis of the onboard camera mounted in the vehicle. This optical axis displacement detection apparatus detects a detection reference used when detecting optical axis displacement using template matching. More specifically, template matching is repeated while the template image of the detection reference is displaced from the center of the captured image, which includes the target image of the onboard camera, to the periphery. The position of the image matched to the template image in the captured image is specified as the position of the target image.